The present invention relates to a display for a vehicle, and more particularly to a display for an aircraft flight management system that also displays terrain features.
Modern map displays, particularly those used in aircraft for flight planning and monitoring, are capable of displaying a considerable amount of information such as flight planning information and terrain information. The terrain information consists of situational awareness (SA) terrain and terrain cautions and warnings that, among other things, may indicate where the aircraft may potentially impact terrain. The flight planning information consists of flight path information, altitude information and other information useful to a pilot or crewmember in following and anticipating the path and altitude of the aircraft over the ground.
A graphic display of a flight path provides better spatial understanding of the planned flight path and therefore reduces the navigational workload for a flight crew. In particular, when an altitude-to-color-coded, relief-shaded terrain representation is used as an underlay for a flight path display, the relative positioning of the flight path to the terrain features can be seen. This aids in detecting potential flight path conflicts with terrain as well as planning for optimal paths around potentially hazardous areas.
It is important, however, that information displayed in integrated displays be properly balanced in order that a flight crew may quickly interpret the contents of the display. Lateral terrain maps are often used as the main background for depicting other navigational and graphical flight planning information. When terrain threats are present, terrain maps highlight the nature and location of the impending threat. In addition, the maps are used for overall situational awareness purposes.
Lateral terrain maps are typically produced by color encoding of altitude and elevation information at discrete regularly spaced locations. Shading techniques may be applied to vary the intensity of the colors in order to model terrain relief features.
However, avionics terrain displays must cover large segments of the world with different scale, resolution, range, and threat handling requirements of multiple tasks, and terrain features are random phenomena. For example, global terrain features from one to 750 nautical miles must be displayed. A fixed terrain shading or feature generation approach may work well in some circumstances but would produce less desirable results in others.
Additionally, system throughput of the computers generating the displays limits the amount of terrain data available to represent features. Complex optical modeling for good visual effects is often computationally prohibitive for on-board real-time systems.
The instant invention addresses the aforementioned difficulties by significantly reducing the computation and data load for producing the flight plan and terrain display for flight management systems. This is accomplished by the use of a terrain relief contrast adjustment parameter, based on a statistical terrain roughness measure, to compute optimal terrain presentation for current display conditions. The contrast adjustment parameter allows situation dependent map presentation to enhance, for example, for caution and warning situations, or de-emphasize the terrain map features for balanced presentation along with foreground symbology